Automatic train control system



p 1933. c. s. BUSHNELL AUTOMATIC TRAIN CONTROL SYSTEM Filed Jan. 23, 1931 2 Sheets-Sheet l ATTORNEY I VE TOR 6? BY Z/M I! 0% 7 NM. T WWI TU M l E 3 Ms AUTOMATIC TRAIN CONTROL SYSTEM Filed Jan. 23, 1931 2 Sheets-Sheet 2 FIG.3. w

I 1 iv 2 1 i I o 16W 155 w RT 1 A 34w? RAE 6 1 1 p O wTTORNEY Patented Sept. 12, I933 PATENT orrics 1,926,854 AUTOMATIC TRAIN CONTROL SYSTEM Charles S. Bushnell, Rochester, N. Y., assignor' to General Railway Signal Company, Roches' ter, N. Y.

Application January 23,

13 Claims.

This invention relates to automatic train control systems, and more particularly to a system in which restriction in the progress of the train is transmitted from the trackway to the moving vehicle only near the entrance to a block.

The system of the present invention as illustrated contemplates the provision of a motor stop mechanism along the track, which moves a stop trip into position when trafilc conditions in advance are dangerous. Since the motor stop mechanism is rather expensive and since it would be desirable to not only stop the train under dangerous traffic conditions but also set-up a continuing speed limit, it is proposed in accordance with the present invention to provide two trip elements along the track, one of whch imposes a continuously effective speed limit on the passing train, whereas the other trip element applies the brakes of the train on the time-distance principle unless the train passes the control point at an exceedingly low speed, of say, two miles per hour or less, this stop element being actuated to its inactive position a predetermined time after the approaching train gets within a predetermined distance of this stop arm.

Other objects of the present invention reside in the provision of means for releasing the speed limit set up by the car-carried apparatus when the train enters favorable traffic territory.

In describing the invention in detail reference will be made to the accompanying drawings, in which:

Fig. 1 shows conventionally a portion of a railway system with wayside signals and the trackway apparatus of the present invention, together with the car-carried apparatus illustrated on a conventionally depicted railway car;

Fig. 2 shows on an enlarged scale the means for latching the stop trip in its inactive position and latching the speed trip in its active position;

Fig. 3 shows the manner in which the car-carried apparatus of Fig. 1 would be modified for locomotives or cars running either end forward;

Fig. 4 illustrates conventionally a system embodying features of speed determined by the time distance interval principle the same as shown in Fig. 1, except that the fixeddistance entering into the speed distance interval formula is confined to the car-carried apparatus instead of to the trackway apparatus as shown in Fig. l.

Referring to Fig. 1 of the drawings, the track rails 1 have been shown'divided into blocks by insulating joints 2, of which the blocks I and J I; and the adjacent ends of blocks H and K only have been shown, the normal direction of traffic tinctive exponents, and the description of the ap- 193'1. Serial No. 510,693

being from leftto right as indicated by the arrow. Since the apparatus for each block is the same, like parts of each block havebeen designated by like reference characters having dis paratus of one block will suffice. At the entrance to the block I there is provided a signal. S which is controlled through the medium of a track relay T, a home relay HR and a distant relay D. Also, at the entrance to each block there is provided a stop trip element ST, and a reduced speed trip element RT, which trip elements are operated to their active or inactive position by the motor stop mechanism MSM. Also, in the rear of each signal S there is provided a reset magnet RS, which under favorable trafiic conditions in advance is energized by alternating current derived from the transformer TF, which reset magnet inductively acts upon the receiver R on the car to energize the reset relay RR. On the railway vehicle conventionally represented by the wheels and axles 10, is carried suit able car-carried apparatus including the electropneumatic brake applying valve EPV, which is normally energized through a stick circuit and which if deenergized applies the brakes preferably of an air brake system of the normally charged brake pipe type, an air switch AS being employed for releasing the brakes when the brake pipe pressure in the brake pipe Bl? has been. reduced to a predetermined value. This electropneumatic valve EPV is also under the control of speed contact 12 actuated by the speed responsive device SD, which device SD is driven from the axles 10 of the vehicle through suitable means conventionally illustrated by the dotted line 13. This speed contact 12 is rendered effective by openingof the front contact 14 of the speed relay SR, and this speed relay SR is deenergized upon opening of the speed arm contact 15 forming apart of the reduced speed arm RA, which is actuated when this arm RA passes the reduced speed trip element ET in its active position. Similarly, the electro-pneumatic valve EPV is deenergized upon opening of the contact 16 of the stop arm SA, which contact 16 is opened upon passage of theyvehicle by a stop trip element ST in its active position. Having now briefly mentioned the essential elements of the train control system of the present invention conventionally illustrated, it is deemed expedient to consider the operation of the system to clearly ascertain the co-ordination of the various elements and the manner in which the train may be controlled during its progress along the track.

Operation Under normal clear conditions, that is when three blocks in advance of a particular signal location, such as signal S, are unoccupied, the home relay HR is energized through a circuit including the line wire 19 and the front contacts 18 and 20 of the track relays of the next two blocks in advance. Similarly, the distance relay D is energized through a circuit which may be traced as follows:beginning at the terminal of a suitable battery, contact 22 of the motor stop mechanism MSM of the next block in advance assuming its inactive clear position, wire 23 front contact 2a' 'of the home relay HR wire 25, front contact 26 of the home relay HR, wire 2'7, winding of the distance relay D, to a common return wire C connected to the other terminal of said battery. The motor stop mechanism MSM is under normal clear traffic conditions energized through the following circuit:beginning at the terminal of a suitable wayside battery, front contact 30 of the home relay HR, wires 31 and 32, field and armature of the motor M to the other terminal of said battery. There is also an auxiliary circuit for the motor M including a back contact 59 of track relay T. Similarly, the reset electromagnet RS is normally energized by alternating current through the following circuit:beginning at the secondary winding of the transformer TF, which transformer is preferably energized by commercial 60 cycle alternating current, wire 34, front contact 35 of the relay HR, wire 36, winding of the reset magnet ES, to a common return wire C connected to the other end of said secondary winding. Under clear traffic conditions the signal S, which signal, although light signals may be used, has for convenience been illustrated as a semaphoresignal, is maintained in its clear proceed position by the energization of its clearing circuit which may be traced as followsz-beginning at the terminal front contact 38 of the relay HR, wire 39, front contact 40 of the relay D, clearing wire cl, signal mechanism of the signal S, to the common return wire C connected to the other terminal of said battery. With the distant relay D deenergized and the home relay HR energized the caution circuit including the caution wire ca is closed.

Referring now to the car-carried apparatus the speed relay SR is normally energized through the following circuit-beginning at the terminal of a car-carried battery, contact 15 of the reduced speed arm RA, wire 42, stick contact 43 of the relay SR, wires 44 and 45, winding of the relay SE to the other terminal of said battery. Similarly, the electro-pneumatic valve EPV is normally energized through the following stick circuit:beginning at the terminal of the car battery, normally closed contact l6-of the stop arm SA, wires 4'? and 48, front contact 14 of the speed relay SR, wires 49 and 50, stick contact 51 of the device EPV, wire 52,- winding of the device EPV to the other terminal of said battery. Also, under normal clear traffic conditions of the car-carried apparatus the high speed light BL is energized through a circuit which may be traced as follows:beginning at the terminal of the car battery, contact 54 of the car cut-out switch L, wire 55, front contact 56 of the speed relay SR, wire 57, high speed light HL to the other terminal of said car battery.

Let us now assume that the railway vehicle 10 proceeds in the normal direction of trafiic, from left to right, under favorable traiiic conditions in advance, and with the track apparatus in the condition as illustrated in the drawings. The passage of the train by the reduced speed trip element RT will have no eiiect, because this trip RT is in its clear non-engaging position. As soon as the first axle of the car 10 passes into the block I it will effect deenergization of the track relay T and close a second circuit for the motor M, which circuit includes the back contact 59 of the track relay T. Since, however, the motor M is already energized the position of the trip elements RT and ST will not be changed, so that these elements RT and ST will remain in their normal inactive position, and the passage of the train thereby will not in any way be affected thereby, except that the passage of the receiver R over the reset magnet RS will result in momentary energization of the car-carried transformer CTF through its tuned circuit including the condenser 60, which circuit is tuned to the frequency transmitted along the trackway and supplied to the various tran formers TF TF etc. With the car-carried transformer CTF momentarily energized the reset relay BR will be momentarily energized by direct current rectified by the double wave rectifier RF, which rectifier is one of the multiple plate copper oxide type.

Momentary energization of the relay RR will effect momentary closure of its contact 61, but since the speed relay SR is already energized the momentary closure of the contact 81 will not perform any useful function at this time.

Let us now assume that the block K is occupied by another train and that its track relay '1" is deenergized. Deenergization of the track relay T will res it in deenergization oi the home relay HR and the distant relay D Deenergization of the home relay HR will result in deenergization of the motor of the stop mechanism MSM so that the trip elements ST and RT will assume their active dotted position. Also, deenergization of the home relay HR through the medium of its contact 24 will effect deenergization of the distant relay D, thereby actuating the signal S to its caution position. Obviously, deenergization of the home relay H'R will actuate the signal S to its danger position, and deenergization of the home relay HR will actuate the signal S to its stop position. Summarizing, the presence of a train in the block K will actuate the first and second signals in the rear to the danger position and will actuate the third signal in the rear to its caution position, and will place the trip elements of the train control apparatus at the first and second signal, namely the signals S and S in the rear thereof in their active position, the train ahead being assumed to occupy the block K. It is thus noted that the signal system is one of the A one-block-overlap type.

Let us now assume that the train illustrated in the drawings is occupying" the block H and that it is moving in the normal direction of traffic toward the train occupying the block K. As the 7 train illustrated enters the block I it will not in any way be affected by the trip elements ST and RT, since these trip elements assume their inactive position, but the engineer will reduce the train speed because he is passing the signal S at caution, and if he operates his train in accord- A ance with the rules he will have reduced his speed to. a low value, of, say, 15 miles per hour when he approaches the end of the block I. If the signal S is still in the stop position, as we will assume for convenience, the engineer must reduce his ,r in) 10 enters the block J the reduced speed arm EA will be engaged by the trip clement 3T thereby momentarily opening the contact 15 and effecting deenergization of the stick relay SR. Since the home relay HR is deenergized the contact35 is open and the reset magnet RSS is deenergized, so that the stick relay SR will remain deenergized. This entrance of the train in question into the block J will of course effect deenergization of the track relay T and the dropping of the contact.

59 of this track relay will close the auxiliary circuit for the motor M Proceeding on the assumption that the train is moving at less than two miles per hour, the motor M will have operated the trip elements RT and S1 to their inactive position before the stop arm SA can engage this.

trip element ST so that the train may proceed into the block J without a brake application, this because the speed contact 12 is now closed and dropping of contact 14 of relay SR as a result of momentary opening of contact 15 of reduced speed arm RA striking trip arm RT cannot deenergize the value EPV. The train may, however, not move very fast, because its speed is restricted by the contact 12 of the speed responsive device SD, this because the contact 14 normally shunting the speed contact 12 was opened upon the entrance of the train into the block J. This contact 12 is preferably closed only at speeds below a medium value of, say, 15 miles per. hour, so that the engineer must keep his train speed below 15 miles per hour to prevent deenergization of the electropneumatic brake applying valve EPV. Also, with the stick relay SR now deenergized the high speed lamp HL is deenergized and the low speed lamp LL is energized, through the following circuit:- Beginning at the terminal contact 54 of the cut-out lever L, wire 55, back contact 56 of the relay SR, wire 63, speed contact 64, wire 65, low speed lamp LL to the other terminal of said battery. It may be pointed out here that speed contact 64 preferably opens at a slightly lower speed than does the contact 12, this to forewarn the engineer of a brake application if his speed is increased further.

Let us now assume thatthe vehicle illustrated passes a signal S at a slightly higher speed than two miles per hour with the block K occupied. Under this condition, the train will travel the distance d in less time than the time r quired for the motor M to return the tripelements ST and RT to their clear position, so that the stop arm SA is actuated by its engagement with the trip element 8T thereby effecting momentary opening of the contact 16 and effecting opening of the stick circuit for the device EPV and deenergization of this device, thus resulting in a brake application.

This brake application will bring the train to a stop and as soon as the brake pipe has been vented to a predetermined extent the spring 66 of the air switch AS will close its contact 67, against the reduced action of the brake pipe pressure, thereby closing the following pick-up circuit for the device EPV:-beginning at the terminal of the car battery, stop contact 16, wires 17 and 68, speed contact 12 of the speed responsive device SD, wires 69, 49, and 70, contact 6'? or" the air switch AS, wires '71 and 52, winding of the device EPV to the other terminal of said battery. As soon as the device EPV picks up in response to the closure of the pick-up circuit just traced, this device EPV will be stuck up through its stick circuit which includes its stick contact 51. Although-the brakes have been released in response to closure of the contact 67, the speed relay SR remains deenergized and the train may only proceed at the restricted speed limit imposed by the speed contact 12.

Let us now assume that the train which occupied the block K has proceeded in an easterly direction to a point where the home relay HR is energized, under which condition the reset magnet RS will be energized by alternating current derived from the transformer TF and flowing through the front contact 35 of the home relay HRF. If the train under consideration now passes by the signal S the reset magnet RS will transmit alternating current to the car-carried transformer CTF through the medium of the receiver R, thereby energizing the reset relay RR through the medium of the rectifier RF. This momentary energization of the reset relay RR closes the following pick-up circuit for the speed relay SR:- beginning at the terminal front contact 61 of the reset relay RR, wires '73 and 45, winding of the speed relay SE, to the other terminal of said car battery. The closure of this circuit will of course pick up the speed relay SR and as soon as this relay is picked up it will be stuck up through its stick circuit heretofore traced.

The cut-in lever L is a lever that must assume its active solid line position in order to allow power to be applied to the locomotive. In the case of a steam locomotive this would be a valve in the steam pipe, whereas in an electric locomotive it would include a contact for carrying current from the thirdrail shoe or the trolley, as the case may be, to the motormans controller connected to the car motors. This lever L is preferably located out of convenient reach of the motorman or engineer so that he is unable to move the lever L to the dotted position while his train is coasting, v

for ii" he could conveniently do this he might cutthe trip elements ST and ET. This motor stop mechanism includes a crank 80, which crank assumes the solid line position when the motor M is energized but assumes the dotted position when the motor M is deenergized, and this crank 30 through the medium of pitman rod 81 operates the lever 82 connected to the square crank shaft 83 as through the medium of the clamp bolt 84 (see Fig. 2). The lever 82 operates the crank 85 through the medium of the connecting rod 86, and the crank 85 operates the reduced speed trip element RT through the medium ofanother square shaft 8'7. Attention is directed to the fact that the connecting rod 86 is connectedto the lever 82 through the medium of the block 90 pivotally secured to the lever 82 as by pin 90. The connecting rod 86 is slidably connected in the block 90 and is held in position by the compression spring 91 secured between the block 90' and the stop member 92. Should the motor stop mechanism MSM forany reason get out of order the reduced speed trip RT would be operated toward the right to its active position, in which position the pin 93 may be dropped through a hole in the connecting rod 86 and into hole in a plate 94 fastened to the ties of the railway track, so that a speed limit would be enforced each time the train passed the signal location at which the trip element RT has been permanently fixed in its active position. In order, however, to avoid the stop trip element ST from also being active and enforcing a brake application irrespective of the governor SD, the stop trip ST may be moved to its inactive position under which condition the latch 95 will engage the notch 96 in the connecting rod 86, thus holding the stop trip element ST in its inactive position.

In some cases it is desirable to provide train control on a locomotive when it is operating tender first, and similarly electric locomotives are generally constructed to be operated either end first, and for such equipment it may be desirable to provide duplicate trip arms on the locomotive and a directional switch for selecting the proper arm for each direction of travel; an arrangement of this kind has been shown in Fig. 3 of the drawings.

As shown in Fig. 3 the contacts on the reduced speed arms RAE and RAW have been shown connected in series through the medium of wire 42 in the stick circuit of the speed relay SR, whereas the contacts of the stop arms SAE and SAW have been shown connected in multiple and selected one at a time through the medium of the reversing switch RV in the stick circuit of the electropneumatic valve EPV. The letter E in the deference characters for these speed and stop arms and their associated contacts E and 16E designate east bound travel and the letter W desig nate west bound travel. The manner in which the apparatus shown in Fig. 3 is coordinated with the rest of the car-carried apparatus is readily understood by reason of the fact that like devices and like wires have been designated by the same reference characters. The reversing switch RV assumes the solid line position when the car 10 moves from left to ri ht and assumes the dotted position when the car moves from right to left, this operation being accomplished by suitable friction means such, for instance, as shown in the application of H. B. Taylor, Ser. No. 380,379 filed July 23, 1929.

In the arrangement shown in Fig. 1 the speed limit at which a train may pass over a stop trip element ST is determined by the distance d that the train must travel after the first wheels and axles of the train have entered the track circuit, this distance being the same as the distance between the trip elements RT and ST, because the trip element RT presumably engages the carcarried arm RA just at the moment that the first axle enters the next block in advance. In order to simplify the wayside construction it is proposed in accordance with the invention shown in Fig. 4 to eliminate one of the trip elements along the railway track and to employ the remaining trip element TE for actuating both the speed reducing arm RA and the stop arm SA. This is accomplished by placing these arms RA and SA so on the car that they travel through the same path along the railway track, namely the path in which the trip element TE is located. Further, these trip arms SA and RA are located a distance d apart, so that the trainmay travel this distance d during the time that the tripelement TE is operated from its active to its inactive position when the train is traveling at its low speed limit of two miles per hour. If, the tripping element TE has operated the contact 15 of the arm RA, the train must travel a distance d before this trip element TE strikes the arm SA to open the contact 16, and if the train is traveling sufficiently slow the trip element TE will have in the meantime assumed its inactive position, in which event no brake application will result unless the train thereafter exceeds the medium speed limit.

Having thus shown and described several embodiments of the invention conventionally but rather specifically, it is desired to be understood that the particular embodiments of the invention illustrated have been selected for the purpose of facilitating describing the invention, its mode of operation and the various interrelated functions that may be accomplished thereby, and has not been selected for the purpose of showing the scope of the invention or the exact construction preferably employed in practicing the same, and that various changes, modifications and additions may be made to adapt the invention to the particular problem encountered in practicing the same, all without departing from the spirit or scope of the invention or the idea of means underlying the same, except as demanded by the scope of the following claims.

What I claim as new is:-

. l. In'combination with a railway track and a vehicle moving thereon, of means partly on the vehicle and partly on the trackway for transmitting an impulse to the vehicle at two different closely spaced positions of the vehicle on the track of which the first is effective only under adverse trafiic conditions and of which the second will occur only under adverse trafiic conditions with the train traveling above a predetermined low speed, a brake control device normally energized by a stick circuit, a speed control relay normally energized by a stick circuit, a speed controlled contact open if the train exceeds a predetermined speed limit normally shunted by a front contact of said speed controlled relay, and means for momentarily opening the stick circuit of said speed control relay in response to the first impulse and momentarily opening the stick circuit for said brake control device in response to said second impulse.

2. In combination with a railway track and a vehicle moving thereon, of means partly on the vehicle and partly on the trackway for transmitting an impulse to the vehicle at two different closely spaced positions of the vehicle on the track of which the first is effective only under adverse traflicconditions and of which the second will occur only under adverse traflic conditions with the train traveling above a predetermined low speed, a brake control device normally energized by a stick circuit, a speed control relay normally energized by a stick circuit, a speed controlled contact open if the train exceeds a predetermined speed limit normally shunted by a front contact of said speed control relay, means for momentarily opening the stick circuit of said speed control relay in response to the first impulse and momentarily opening the stick circuit for said brake control device in response to said second impulse, and means for manually adjusting said means on the trackway to render said first impulse eifective under all trafiic conditions ahead and to prevent said second impulse being transmitted irrespective of the tramc conditions.

3. In combination with a railway track and a vehicle moving thereon, of means partly on the vehicle and partly on the trackway for trans mitting an impulse to the vehicle at two different closely spaced positions of the vehicle on the track of which the first is effective only under adverse trafiic conditions. and of which the second will occur only under adverse traificconditions with the train traveling above a predetermined low speed, a brake control device normally energized by a stick circuit, a speed control relay normally energized by a stick circuit, a speed controlled contact open if the train exceeds a predetermined speed limit ncrmally shunted by a front contact of said speed control relay, means for momentarily opening the stick circuit of said speed control relay in response to the first impulse and momentarily opening the stick circuit for said brake control device in response to said second impulse, and inductive means partly on the vehicle and partly along the trackway for restoring speed control relay to normal.

e. In ccmbinationwith'a railway track and a vehicle moving thereon, of means partly on the vehicle and partly on the trackway for transmitting an impulse to the vehicle at two difierent closely spaced positions or" the vehicle on the track of which the first is eiiective only under adverse traffic conditions andof which the second will occur only under adverse traffic conditions with the train traveling above a predetremined low speed, a brake control device normally energized by a stick circuit, a speed control relay normally energized by a stick circuit, a speed controlled contact open if the train exceeds a predetermined speed limit normally shunted by a front contact of said speed control relay, means for momentarily opening the stick circuit of said speed control relay in response to the first impulse and momentarily opening the stick circuit for said brake control device in response to said second impulse, means for manually adjusting said means on the trackway to render said first impulse effective under all traffic conditions ahead and to prevent said second impulse being transmitted irrespective of trafiic conditions, and inductive means partly on the vehicle and partly along the trackway for restoring said speed control relay to normal.

5. In combination with a railway track and a vehicle moving thereon, of means partly on the vehicle and partly on the trackway for transmitting an impulse to the vehicle at two difierent closely spaced positions of the vehicle on the track of which the first is effective only under adverse traific conditions and of which the second will occur only under adverse trafiic conditions with the train traveling above a predetermined low speed, a brake control device normally energized by a stick circuit, a speed control relay normally energized by a stick circuit, a speed controlled contact included in the stick circuit of said brake control device and open if the train exceeds a predetermined speed limit normally'but shunted by a front contact of said speed control relay, means for momentarily opening the stick circuit of said speed control relay in response to the first impulse and momentarily opening the stick circuit for said brake control device in response to said second impulse, means for manually adjusting said means on the trackway to render said first impulse efiective under all trafilc conditions ahead and to prevent said second impulse being transmitted irrespectiveof trafiic conditions, and means partly on the vehicle and partly along the trackway for restoring said speed control relay to normal when trafiic conditions in advance are favorable.

6. In combination with a railway track and a vehicle moving thereon, of means partly on the vehicle and partly on the trackway for transmitting an impulse to the vehicle at two difierent closely spaced positions of the vehicle on the track of which the first is eiieotive only under adverse trafiic conditions and of which the second will occur only under adverse traffic conditions'with the train travelingabove a predeterit :led low speed, a brake control device normally energized by a stick circuit, a speed control relay normally energited by a stick circuit, a speed controlled contact op f the train exceeds a predetermined speed ln tincluded in the stick circuit of brake control device and normally shunted by a front contact of said speed control relay, incl-sis for momentarily opening the stick circuit of said speed control relay in response to the first impulse and momentarily opening the stick circuit for said brake control device in response to said second impulse, and inductive means partly on the vehicle and partly along the trackway for restoring said speed control relay to normal. I

'7. In combination with a railway track and a vehicle moving thereon, of means partly on the vehicle and partly on the trackway for transmitting an impulse to the vehicle at two different closely spaced positions of the vehicle on the track of which the first is efiective only under adverse traffic conditions and of which the second will occur only under adverse traffic conditions with the train traveling above a predetermined low speed, a brake control device normally energized by a stick circuit, a speed control relay normally energized by a stick circu a speed controlled contact open if the train exceeds a predeteinined speed limit included in the stick circuit of said brake control device and normally shunted by a front contact of said speed control relay, means for momentarily opening the stick circuit of said speed control relay in response to the first impulse and momentarily opening the stick circuit for said brake control device in response to said second impulse, means for manually adjusting said means on the trackway to render said first impulse effective under all trafiic conditions ahead and to prevent said second impulse being transmitted irrespective of traffic conditions, and inductive means partly on the ve hicle and partly along the trackway for restoring said speed control relay to normal.

8. In a train control system, a trackway, two impulse communicating devices at substantially the same point along the same trackway, automatic means controlled in accordance with tralfic conditions to at times render said devices active and at other times render them inactive, and manually operable means for rendering one of said devices permanently effective and rendering the other device permanently inefiective.

9. In a train control system, a trackway, two impulse communicating devices at substantially the same point along the same trackway, automatic means controlled in accordance with trafiic conditions to at times render said devices active and at other times render them inactive, and means for manually rendering one only of said two devices permanently ineffective.

'10. In combination, two trackway train control trip devices operated to the active and the inactive position by the same power operated means but one placed in advance of the other along the track and both assuming the active condition under adverse trafilc conditions ahead, means for controlling said power operated means upon the approach of a train under such adverse traflic conditions to render the second of said trips inactive by the time said approaching train reaches it if such approaching train moves below a predetermined average speed, and car-carried appa ratus on said approaching train for restricting the progress of the train upon engagement with said first trip and for applying the brakes of the train upon engagement with the second trip.

11. In combination, two trackway train control trip devices operated to the active and inactive position by the same power operated means but one placed in advance of the other along the track and both assuming the active condition under adverse trafiic conditions ahead, means for controlling said power operated means upon the approach of a train under such adverse trafiic conditions to render the second of said trips inactive by the time said approaching train reaches it if such approaching train moves below a predetermined average speed, car-carried apparatus on said approaching train for restricting the progress of the train upon engagement with said first trip and for applying the brakes of the train upon engagement with the second trip, and other means controlled in accordance with trafIic conditions for removing the imposed restriction on the progress of the train.

12. In combination, two trackway train control devices one placed in advance of the other along the track and both assuming the active condition under adverse trafiic conditions ahead, means for controlling said devices upon the approach of a train under such adverse trafiic conditions to render the second of said devices inactive by the time said approaching train reaches it if such approaching train moves below a predetermined average speed, and car-carried apparatus on said approaching train for restricting the speed of the train below a specific value following the passage of such train by said first device and for applying the brakes of the train irrespective of its speed upon passage of the train by the second device when active.

13. In combination, two trackway train control devices one placed in advance of the other along the track and both assuming the active condition under adverse traffic conditions ahead, means for controlling said devices upon the approach of a train under such adverse traffic conditions to render the second of said devices inactive by the time said approaching train reaches it if such approaching train moves below a predetermined average speed, car-carried apparatus on said approaching train for restricting the speed of the train below a specific value following the passage of such train by said first active device and for applying the brakes of the train irrespective of its speed upon passage of the train by the second active device, and other means controlled in accordance with traflic conditions for removing the imposed restriction on the speed. of the train.

CHARLES S. BUSHNELL. 

